Pulp screen



Oct. 3, 1961 w. F. MATHEWSON4 PULP SCREEN 8 Sheets-Sheet 1 Filed Jan.28, 1957- m CM Oct. 3, 1961 w. F. MATHEWSON PULP SCREEN 8 Sheets-Sheet 2Filed Jan. 28, 1957 rm/W57 Oct. 3, 1961 w. F. MATHEWSON 3,002,521

PULP SCREEN Filed Jan. 28, 1957 8 Sheets-Sheet 3 f v alian-QM A T rams5y Oct. 3, 1961 w. F. MATHEWSON PULP SCREEN 8 Sheets-Sheet 4 Filed Jan.28, 1957 Oct. 3, 1961 w. F. MATHEWSON 3, 1

. PULP SCREEN Filed Jan. 28, 1957 8 Sheets-Sheet 5 HTTOR/VEY PULP SCREEN8 Sheets-Sheet 6 Filed Jan. 28, 1957 0 0 W M M C N m m m a W32 m w a 2-M 1J6 6 4 M Oct. 3, 1961 w. F. MATHEWSON PULP SCREEN 8 Sheets-Sheet 7Filed Jan. 28, 1957 IA/I/EAI T017 W/L FRED EH19 T/IEWfO/l mam v t 3,1961 w. F. MATHEWSON 3,002,621 I PULP SCREEN 8 Sheets-Sheet 8 il m vmrol? 74 mums-,0 lV/YTHZWMA/ United States Patent 3,002,621 PULP SCREENWilfred F. Mathewson, 261 St, Weymouth 10, Mass. Filed Jan. 28, 1957,Set. No.'636,807 8 Claims. (Cl. 209250) This invention relates to pulpscreens and particularly to pulp screens of the type provided with acylindrical screen'member having a cylindrical screening wall and whichrotates about a horizontal axis, and means for delivering unscreenedpulp stock to the interior of said screen member, the screeningoperation involving the 110w of the acceptable portion'of the pulp stockthrough the screening wall from the interior isms exteriorthereof.

One object of the present invention is to provide a novel screen memberof this type in which the screening wall has an increased screeningarea, with the result that the screen will deliver an increasedpercentage of acceptable stock from any given amount of nnscrleened pulpstock during any one screening operation.

Another object of the invention is to provide a novel screen member inwhich the screening wall is formed of a flat wire which is bent edgewiseinto the form of a cylindrical coil, the adjacent turns of the coilbeing spaced from each other a distance to provide screening'slots ofthe desired width.

A still further object of the invention is to provide a pulp screen ofthis type in which the unscreened stock is delivered onto the interiorface of the cylindrical screening wall in the form of a sheet whichextends from one end to the other of the screen member.

Another object of the invention is to provide a pulp screen of the abovetype in which the opening through which the unscreened stock isintroduced into the casing and the openings through which the screenedstock and the tailings are discharged from the casing are located in thesame end of the casing.

Another object of the invention is to provide a novel pulp screen whichis so constructed as to facilitate the removal of the cylindrical screenas a unit from the casing. Other objects of the invention are to improvepulp screens in various ways which will be set forth in the followingdescription.

,In the drawings:

FIG. 1 is an eievation showing the .end of the pulp screen through whichthe unsereened pulp stock is .delivered thereto and screened stock andt-ailings are disharge FIG. 2 is a view showing the other 9nd of thepulpscr e FIG. 3 is a section on the line 3.,,-3, FIG. 1-;

MG. 4 is a section on the line 4-74, FIG .:3;

FIG. 5 is a section on the line 5?5, FIG. 3;

FIG, 6-is an end view of the screen -,elem ent-;

FIG. 7 is a section on the line '7T-7, FIG. 5;

FIG. 8 is a perspective view of the driving gear by which the :screenelement is rotated;

FIG. 9 is a fragmentary perspective Niew of -.a portion o th an pl of te cy ndr cal screen element;

G- 0 -a .t a en a y pe spe ve ri ewsshowin a det ilo t e ssreenel m m;

.11 i .as .ma y:sestiesal wiew of thetser en e ment;

HQ .12 i a t esm marv e t nal ew ho in the m nne is ich them c eedpulp-s oc i de ve ed nt nterio ra e-Qt t s re nin o hes een clea esIls n b sc ee emb dyin thi inv nt o ml des 1a casing, indicatedgenerally at 3, and a cylindrical sereeg:

elemen ind a d .-.se.n. a y at 4. which i .1Q9%$ -t 3,662,621 PatentedOct, 3, 196 1 in the casing and is mounted for rotation about ahorizontal axis," said screen element having a cylindrical screeningwall indicated generally at 5 and which will be hereinafter described indetail. The casing ,3 inoludes two end members and a body portion whichencloses the screen member. One of theend members is indicated at 6 andthe other at 7. The body portion includes a bottom body member 8 and atop body memher 9. The bottom body member 8 is secured to the inner face10 at the end member'6, said bottom body member having a downwardlyprojecting flange 11 which overlies said inner face 10 of the end member6 and is secured thereto by bolts 12.' The bottom body member it extendsthrough the end member 7, as best seen in i8. 3, and is provided with anoutwardly extending flange 13 which overlies the outer face of the endmem her I of the casing and is bolted thereto by suitable bolts 14.

The end wall of the casing which is seen in FIG. 2 and which constitutesthe right hand end wall in FIG. 3 :iS constituted by a plate 15 and aremovable closure member 16. The plate 15 is bolted to the flange 13 ofthe bottom body member 8 by the bolts :14 above referred to, and thisplate together with the closure member 16 constitutes the complete endwall for the casing. The closure member 16 is shown as a circularmember, the lower peripheral half of which is removabl-y mounted in asemicircular support member 1-7 which is bolted to the end plate 15 bybolts 17a and is shaped to provide a groove 13 in which the lower edgeof the tale, sure 16 is received, as best seen in IG. 3.

This closure may, if desired, be made of some parent material so thatthe screening operation the cas g may be observed.

T nd m m 6 has the general s p s own i FIG. 1 and constitutes theclosure for the opposite .end of the easing,.-that .is, the left handend in FIG. 3, The upper por of he s g bove th end member 6.-i.s closedby a plate 19 which is secured by bolts 21 to a flange 29. with whichthe e d n mbe s P 0 The upper body member 9 encloses the upper half ofhe sc en m b 4 a d t e lower ed o sai upper member are secured to thetop edges of the lower body member by means of bolts 22.

he screen mem e 4 s moun n a sha t 23, n an i w ic i PPQ s i ro ler ea ns .4 c rr ed y t nd memb r's t e h r and of t e shaf b in .s p Q i b rinW thin th scr en 4 a l be p tl e crib d- The s insi is l s r en elemen-;itw u s n en s pp t n plate 25 t w sk: ne a d Pi th s e n walla isrigidly secured and which is fast on one end of the ha 3- Ills end-P ate2. t u closes n end-of the y l ca sc een ement- The t e end or t 'd i sr e e em n s o e asser s n an la plat w h c o s as a s l h ua d n i h ale to as ef a d an 0f the s reeni -wa l a shown best in F168. Thisannular plate 26 has ,acentral op .27- e e d-p a e 2 hu car i th i 1 weis -te n me ber a j sho n a be n -re n orces by radially ,extendingribs254.

It has been stated above that one end of the shaft on which the screenmember is .rnounted has a supporting bearing 24 in the end member .6.The other .end or the shaft, that is, the right hand end in F16 3, issupported in a bearing carried by a core member 28 which is lo.- catedwithin the screen member 4 and is rigidly secured to the inner face ofthe end member 6 by means of bolts 29, saidcore member having anoutwardly projecting flange 30 through which the bolts 29 extend. Saidcope member 2 i pr vi e w t -a ea box Por ion 1 ich ha a ch mb whisk i rcei ed a ear 3 by i h vided with roller bearings 35 in which the gear 33is mounted, and since said core member is rigidly connected to the endmember 6, it provides a substantial and fixed support for the bearings35 and hence for the gear 33. The shaft 23 is thus provided withsuitable bearings at each end thereof. If desired the shaft 23 may beenclosed in a tubular member 102 which extends from the :end member 6 tothe gear box 31.

- The jaw clutch connection between the gear 33 and the .hub 34 of theplate 25 is illustrated in FIGS. 8 and 9.

The gear 33 presentsa hub portion 36 which extends through the end wall37 of the gear casing 31 and which is provided with the jaw projections38 which have an interlocking engagement with complementary jawprojections 39 with which the hub 34 of the end plate 25 is provided.Said end plate is secured to the hub 36 of the gear 33 by means of bolts40 which extend through the hub portion 34 of the plate and screw intoscrew-threaded sockets 40a with which the hub portion 36 of the gear 33is provided.

The gear 33 by which the cylindrical screen is rotated may be driven inany suitable way. As herein shown,

there is provided a motor 41 mounted on a motor support 42 that issecured to the end member 6. This motor has a driving pulley 43 which isconnected by a belt 44 with a pulley 45 on a drive shaft 46 whichextends through the end member 6 and into the gear box chamber 32. Theouter end of the drive shaft 46 is supported in a roller bearing 48carried by the end wall 37 of the gear box chamber and said shaft 46 hasfast thereto a small gear 49 which, in the embodiment herein shown, isconnected to the gear 33 through a reducing set of gears. As hereinshown, the gear 49 meshes with a larger gear 50 which has integraltherewith a small gear 51 that in turn meshes with the gear 33, as bestshown in FIG. 5.

The wall 37 of the gear box is shown as a removable element, it beingsecured to the wall portion 53 of the gear box by suitable bolts 54. Thegear element 50, 51 is shown as mounted in roller bearings 55, 56, thebearing 55 being mounted in the main portion of the wall of the gear boxand the bearing 56 being mounted in the removable cover portion 37. Saidcover portion also has integral therewith an annular inwardly directedportion 48a in which the roller bearings 48 are supported.

The shaft 46 is shown as extending through a protecting tube 103 whichextends from the end member 6 to the gear box 31.

The screening wall 5 of the screen member 4 is of the type whichpresents a plurality of parallel through slots, each of which has awidth sufficient to permit the acceptable portion of the pulp stock topass therethrough but which is insutficient in width to allow theunacceptable portion of such stock to pass.

In the construction herein shown the screening wall is made from alength of flat wire 76 which is bent edgewise into the form of acylindrical coil having a diameter corresponding to that desired for thecylindrical screen memher, the turns of the flat wire coil being spacedapart the proper distance to provide the necessary through slots 64 insaid wall. This cylindrical coil is supported by a plurality ofsupporting bars 62 which extend from one end of the screen member to theother and are located on the outside of the coil, each supporting barhaving on its inner face a plurality of transversely extending grooves63 in which the edge portions of the various turns of the flat wire coilare received, as best seen in FIGS. 10 and 11. The grooves 63 have awidth equal to the thickness of the flat wire 76 and they are spacedfrom each other properly to maintain the turns of the coil in properrelative positions to form the through slots 64.

The supporting bars 62 are anchored at their ends in the peripheralportions of the end plate 25 and the annular end member 26 of the screenmember. Each bar 62 has rigid therewith at each end a projecting studwhich is screw-threaded at its end, the studs at one end of the barsbeing indicated at 65 and those on the other end at 66. The studs 65 ofthe various bars 62 extend through openings 67 in the peripheral portion68 of the end plate 25 and are anchored in position by means of clamping'nuts 69 which are screw-threaded to the ends thereof.

Said nuts may either be flat sided nuts adapted to be manipulated by awrench or may be provided with a screw driver slot 70, as shown in FIG.11, so that said nuts can be manipulated with a screw driver.

The studs 66 on the other ends of the bars 62 extend through openings 71in a circular ring 72 and said ring is clamped to the bars by means ofclamping nuts 73 screw-threaded to the studs 66. The ring 72 in turn isanchored to the peripheral portion 74 of the annular end member 26 bymeans of clamping bolts 75.

With this construction the screening wall 5 will present a spiral slot64 extending circumferentially of the wall from one end of the screenelement to the other, with a result that the said screening wallpresents a maximum slotted area for screening purposes.

Inasmuch asthe screening wall of the screen element is supportedentirely by the end plate 25, it may be desirable to provide means forreinforcing the screen structure to prevent any sagging or disalinementof the open end thereof.' For this purpose; there is provided an outercylindrical shell member 1000f expanded metal which encircles thescreening wall and one end of which is rigidly secured in some suitableway to the Peripheral edge of the end plate 25, and the other end ofwhich is similarly rigidly secured to the peripheral edge of the ring72.

The core member 28 which contains the gear box 31 is provided with areceiving chamber 77 which is located within the screen element andextends longitudinally thereof. This receiving chamber 77 hascommunication with an inlet opening 78 with which the end member 6 ofthe casing is provided, said inlet opening in turn communicating with aninlet pipe 79 through which uns7creened pulp stock may be delivered intothe chamber The chamber 77 is formed with a delivery nozzle 80 whichextends longitudinally of said chamber and which presents a deliveryopening in the form of a downwardly directed delivery slot 81 throughwhich the unscreened material is delivered onto the interior face of thescreening wall 5. This delivery slot 81 extends s the full length of thescreen element from one end to the other thereof and provides meanswhereby the unscreened pulp stock is delivered onto the interior face ofthe screening wall in the form of a sheet. The delivery slot 81 ispreferably located closely adjacent the interior face of the screen, asshown in FIGS. 4 and 12, and approximately in a horizontal planeextending through the axis of the screen element. Since the deliveryslot 81 is spaced slightly from the screening wall 5, the sheet 82 ofunscreened pulp stock will have a vertical movement for a short distancebelow the nozzle slot 81 before it actually comes into contact with theinterior face of said screening wall. The delivery move ment of theunscreened stock is in the same direction as that of the screening wallas indicated by the arrows in FIG. 12 and preferably the unscreenedstock will be delivered through the delivery slot 81 under sufficienthead so that the velocity of the sheet 82 of said pulp stock issubstantially the same as that of the screening wall.

During the free downward movement of the sheet 82 encased of the pulpbetween the delivery-slot and the point where it contacts with the innerface of the screen, the fibres in the pulp stock will tend to alinethemselves with the direction of flow and thus with the screening slots64. This result is conducive to an increased flow of; acceptableportions of the stock through the slots. The increased screening areawhich the screening wall herein illustrated provides is another factorin produca screen member which will, during a single. screenmgoperation, deliver from a given amount of unscreened stock an increasedpercentage of acceptable pulp stock and a reduced percentage oftailings..

The acceptable portion of stock which is screened through the screeningwall 5 collects in a chamber 84 in the lower portion 8 of the casingandthis chamber has communication with a discharge opening 89 with whichthe end wall 6 of the casing is provided. The acceptable portion of thepulp stock is thus discharged through the opening 89.

Any portion of the pulp stock which does not pass through the screeningwall 5 will remain on the inner face thereof and will be carried by saidscreening wall into a position opposite a shower pipe 90 which is located outside of the screen and which serves to flush from the innerface of the screen any pulp stock which remains thereon. This pulpstock, which constitutes the tailings, drops onto a deflecting apron 91which forms part of the core member 28 and is collected in a chamber 92.Said chamber 92 has communication with a tailings discharge opening 93with which the end memher 6 of the casing is provided and is deliveredthereby to a suitable pipe connection leading to any desired location.

The shower pipe 90 is shown as located in a pipe casing 94 which formspart of the cover portion 9 of the casing. Said cover portion comprisesthe two sections 95 and 96 which are spaced from each other to receivethe shower pipe casing 94, said casing being secured to the edges of thecover sections 95, 96 by means of suitable bolts 97.

I claim:

1. A pulp screen comprising a casing provided with an end member at eachend thereof, a cylindrical screen element within the casing and having acylindrical screening wall, an end plate closing one end of said screenelement, the other end being open, means to rotate the screen elementabout a horizontal axis, a first chamber stationarily supported entirelywithin the screen element to receive unscreened pulp stock, said chamberhaving a delivery nozzle through which the unscreened pulp stock isdeposited on the interior face of said screening wall in the form of adownwardly moving vertical sheet which is parallel to the axis of thescreen element and is located close to said interior face in ahorizontal line extending diametrically of the screen element, saidcasing having a second pulp stock, means to remove the tailingsprogressively from the portion of said interior face of the screeningwall that is approaching the said delivery nozzle during the rotation ofthe screen element, a receptacle member within the screen element toreceive the tailings that are thus removed, one of said end members ofthe casing having an inlet opening communicating with the first chamberand through which unscreened pulp stock is delivered to said firstchamber, and also having an outlet opening communicating with saidsecand chamber and through which screened pulp stock is discharged fromsaid second chamber, and further having a second outlet openingcommunicating with the receptable member and through which the tailingsremoved from the interior face of the screening wall are discharged.

2. A pulp screen comprising a casing having an end member at each end, acylindrical screen element located within the casing and having acylindrical screening wall and an end plate at one end thereof whichcloses said end, the other end of the screen element being open, ahorizontalscreen-supporting shaft extending axially through the screenelement from one end to the other and also through said end plate, thelatter being fixed to said shaft, one of the end members having a firstbearing for one end of said shaft, a bearing support secured to saidendmember and extending into the screen element through its open end andsubstantially to the closed end thereof, said bearing supporting havinga bearing for said shaft located adjacent the closed end of the screenelement, and means to rotate said shaft and the screen member carriedthereby.

3. A pulp screen comprising a casing having an end member at each end, acylindrical screen element located within the casing and having acylindrical screening wall and an end plate at one endthereof whichcloses said end, the other endof the screen element being open, ahorizontal screen-supporting shaft extending an ially through the screenelement and said end plate, the latter being fixed to said shaft, one ofthe end members having a first bearing for one end of said shaft, abearing support secured to said end member and extending into the screenelement through its open end and substantially to the closed endthereof, said bearing support having a bearing for said shaft locatedadjacent the closed end of the screen element, means to rotate saidshaft and the screen member carried thereby, said other end memberhaving an opening in line with the screen element and of a size topermit said screen element and the shaft by which it is supported topass therethrough, and a removable closure for said opening which isseparate from both the screen element and the bearing support, wherebysaid screen element and the shaft to which it is secured is removable asa unit from the casing or replaceable therein through said opening.

4. A pulp screen as defined in claim 3 in which the removable closure isof transparent material.

5. A pulp screen comprising a casing having an end member at each endthereof, a cylindrical screen element within the casing, a horizontalshaft on which the screen element is mounted, a bearing in one endmemher for one end of said shaft, a stationary core member secured tosaid one end member and extending into the screen member, a bearing forthe other end of the shaft carried by said core member, a driving gearaxially aligned with the shaft, a bearing support for said gear carriedby the core member and having a central opening through which said shaftextends, means to rotate the driving gear and a jaw clutch connectionbetween the driving gear and said screen element.

6. A pulp screen comprising a casing having an end member on each end, acylindrical screen element within the casing and having an end platewhich closes one end thereof, the other end of the screen element beingopen, a horizontal shaft on which said end plate is fixedly mounted, abearing in one end member for one end of the shaft, a core membersecured to said one end member and having a portion located within thescreen element, a bearing for the other end of said shaft carried bysaid core element, said core member having a gear box, a driving gearmounded for rotation in said gear box and having a central openingthrough which said shaft extends, means to rotate the driving gear, anda jaw clutch connection between said driving gear and said end plate ofthe screen element.

7. A pulp screen comprising a rotary cylindrical screen element having acylindrical screening wall, means mounting said screen element to turnabout a horizontal axis, a stationary chamber for unscreened pulpsituated entirely within said screen element, said chamber extendingfrom one end to the other of the screen element and being provided witha delivery nozzle having a downwardly opening elongated delivery slotextending parallel to the axis of the screen element and located closelyadjacent the interior face of said screening wall in a. horizontal lineextending diametrically of said 'screen element, said delivery slotbeing constructed to deliver the unscreened pulp in the form of a singlesheet which flows downwardly vertically from said delivery slot onto aportion of the inner face of the screen element which is immediatelybelow a horizontal diametrical plane through said screen element,whereby the downwardly moving sheet of unscreened pulp flows onto theinner face of the screen element at a small angle, and means to rotatethe screen element in a direction in which said portion of the interiorface of the screening wall is moving in the same direction as the sheetof unscreened pulp stock which is delivered thereon.

8, A pulp screen as defined in claim 7 in which the screening wall hasscreening slots extending circumferentially thereof whereby as thevertically moving sheet of unscreened pulp stock comes into contact withthe inner face of the screening wall, said sheet is moving in thelengthwise direction of the screening slots.

References Cited in the fileof this patent- UNITED STATES PATENTSAlexander June 11, Goss July 7, Hang et al. June 18, tadler Feb. 2, LawnIan. 30, Mathewson Oct. 5, Mathewson Oct. 10, Fon tein June 5, DubachJune 5, Sandison'" July 3, Fontein May 6,

FOREIGN PATENTS Norway July 15, Great Britain July 22,

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No3,002,621 October a, 1961 Wilfred F. Mathewson It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

In the heading to the printed specification, lines 3 and 4, for "WilfredF. Mathewson, 261 Franklin St. Weymouth l0 Mass." read Wilfred F.Mathewson, Weymouth, Mass. (261 Franklin St. Boston 10, iass.) column 5,line 56, after second insert chamber exterior to the screen member toreceived screened lines 65 and 66, for "secand" read second column 6line 9 for "supporting" read support line 61, for "mounded" read mountedSigned and sealed this 3rd day of April 1962.

(SEAL) Attest:

' ERNEST W, SWIDER DAVID L. LADD Attesting Officer Commissioner of Paten

